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Objective To find a suitable ecological cultivation measure to solve the problem of root-knot nematode disease of Panax quinquefolium (Panacis Quinquefolii Radix) and the heavy metals accumulating in its roots. Methods Three-year-old P. quinquefolium was treated with four different combinations of microbial inoculant (MI) and garbage fermentation liquid (GFL) [the joint application of ‘TuXiu’ MI and Fifty potassium MI (TF), the combination use of ‘No. 1’ MI and Fifty potassium MI (NF), ‘Gulefeng’ poly-γ-glutamic acid MI (PGA), GFL], and the untreated control (CK). Here, high-throughput sequencing, ICP-MS and UPLC were employed to systematically characterize changes of microbial diversity and structure composition, heavy metals (As, Cd and Pb) content and ginsenoside content among different treatments. Results The results revealed that different MIs and GFL could increase the root dry weight of P. quinquefolium, PGA enhanced it by 83.24%, followed by GFL (49.93%), meanwhile, PGA and GFL were able to lessen root-knot nematode disease incidence by 57.25% and 64.35%. The treatment of PGA and GFL can also effectively reduce heavy metals in roots. The As content in GFL and PGA was decreased by 52.17% and 43.48% respectively, while the Cd and Pb contents of GFL and PGA was decreased somewhat. Additionally, the content of total ginsenosides was increased by 42.14% and 42.07%, in response to TF and NF, respectively. Our metagenomic analysis showed that the relative abundance of particular soil microbial community members related to the biocontrol of root-knot nematode disease and plant pathogen (i.e., Chaetomium in NF, Xylari in GFL, and Microascus in PGA), heavy metal bioremediation (Hyphomacrobium in PGA and Xylaria in GFL), and nitrogen fixation (Nordella and Nitrospira in TF) was significantly increased; notably, potential harmful microflora, such as Plectosaphaerella and Rhizobacter, were more abundant in the control group. Conclusion MI and GFL could improve the quality of P. quinquefolium by modifying its rhizosphere microbial community structure and composition, both of them are beneficial to the development of ecological cultivation of P. quinquefolium.

OBJECTIVE To evaluate the effects of cryopreservation in post-thaw umbilical cord blood units for the survivability of Gram-positive bacteria strains. BACKGROUND Microbial screening is required for all cord blood units (CBUs). Four gram-positive contaminants were documented to survive cryopreservation poorly and isolation of other contaminants were reported. METHODS Forty-eight contaminated CBUs detected with either Staphylococcus epidermidis, Corynebacterium species, Peptostreptococcus or Streptococcus species before cryopreservation were used in this study. CBUs were processed, DMSO-infused and microbial screened before cryopreservation. Post-thaw microbial screening was achieved using 1 and 10 ml inoculants in BACTEC culture bottles. Positive bottles were subjected for microbial identification and results were compared with those from pre-freeze. RESULTS A higher rate of microbial contamination was found using the 10 ml inoculant. Screening of 11 CBUs did not detect any contaminants while 30 CBUs screened detected more than one unknown contaminants and majority of contaminants were identified to be gram-negative species. CONCLUSION A higher inoculation volume used at post-thaw for microbial screening improves contamination detection but leads to the loss of precious cord blood. Some contaminants did not survive cryopreservation or were not identified due to their low microbial levels. Contrasting contaminants found at post-thaw suggest the improvements made in detection and identification of contaminants over the years.

Studying the legume nodule microbiome is important for understanding the development and nutrition of the plants inhabited by the various microbes within and upon them. We analyzed the microbiomes of these underground organs from both an important crop plant (Medicago sativa) and a related legume (M. polymorpha) using metagenomic and culture-based techniques to identify the main cultivatable contributors to plant growth enhancement. Using high-throughput sequencing, culturing, and in planta techniques, we identified and analyzed a broad population of the bacterial taxa within Medicago nodules and the surrounding soil. Fifty-one distinct bacterial strains were isolated and characterized from nodules of both Medicago species and their growth-promoting activities were studied. Sequencing of 16S rRNA gene amplicons showed that in addition to Ensifer, the dominant genus, a large number of Gram-positive bacteria belonging to the Firmicutes and Actinobacteria were also present. After performing ecological and plant growth-promoting trait analyses, selecting the most promising strains, and then performing in planta assays, we found that strains of Bacillus and Micromonospora among others could play important roles in supporting the growth, health, and productivity of the host plant. To our knowledge, the comparison of the biodiversity of the microbiota of undomesticated vs. cultivated Medicago roots and nodules is novel and shows the range of potential Plant Growth-Promoting Bacteria that could be used for plants of agricultural interest. These and other nodule-isolated microbes could also serve as inoculants with rhizobia with the goal of replacing synthetic fertilizers and pesticides for sustainable agriculture.

The objective of this work was to determine the effect of bioproducts on the growth and phytosanitary status of turnip plants, this with the main purpose of determining the viability in the use of ecological alternatives such as chitosan and inoculants made with strains of Bradyrhizobium japonicum, with a view to contribute to the implementation of more sustainable practices in turnip production. The present study took place at the “La Maria” campus of the Quevedo State Technical University, Los Rios province, Ecuador. The methodology that was used was a completely randomized design (dca), consisting of 6 treatments in triplicate; the treatments consisted of the application of: 1) Chitosan of high molecular weight, 2) Chitosan of low molecular weight; 3) B. japonicum; 4) B. japonicum + high molecular weight chitosan; 5) B. japonicum + Chitosan of low molecular weight and 6) control. The turnip seeds were soaked for 2 hours in each of the treatments before planting later, the treatments were applied at 10, 20 and 30 days. To see the differences between the treatments, the Tukey test was implemented (p≤ 0, 05). The results determined that the highest emergence rate of turnip seeds was those obtained embedded with the T5 treatment (Chitosan underweight + bacteria) with a record of 49, 45%. Regarding productive parameters such as: leaf length, plant height, root length and yield per hectare, the treatments that included the use of high molecular weight chitosan stood out, in the same way, it occurred during the evaluation of the state phytosanitary, demonstrating great efficiency in turnip production under the agroclimatic conditions present in the area.

This study aimed to investigate the effects of homo/heterofermentative lactic acid bacteria (LAB) on the quality of corn silage and its rumen digestibility. Maize (Zea mays strain Xingsiyu No. 10), at the early dough stage, was harvested, chopped, ensiled in vacuum bags, and divided into four groups: (1) control (without added bacteria); (2) with the homofermentative LAB Lactobacillus plantarum and Pediococcus pentosaceus (1:1 mixture, 1 × 105 cfu·g−1); (3) with the heterofermentative LAB Lactobacillus buchneri (1 × 105 cfu·g−1); and (4) with the homo/heterofermentative LAB L. plantarum, P. pentosaceus, and L. buchneri (1:1:1 mixture). At 2, 8, 15, 45, and 60 d of ensiling, nutritional quality, fermentation characteristics, and microbial content were assessed. After 60 d, aerobic stability and rumen digestibility tests were performed. The addition of homo- and (or) hetero-fermentative LAB significantly improved the nutritional quality, fermentation characteristics, and microbial content. Addition of the heterofermenter L. buchneri, with or without the homofermenters L. plantarum and P. pentosaceus, improved aerobic stability. The different LAB inoculants increased the degradation rates of dry matter, acid detergent fiber, and neutral detergent fiber of the corn silage by sheep ruminants. Analysis indicated that L. buchneri yielded the best corn silage.

Plant Growth Promoting Bacteria Rhizobacteria (PGPR) is one of the potential bacteria to enhance of Capsicum annuum through inhabitation the growth of pathogenic fungi. This study aimed to characterize PGPR in chili plants (Capsicum annuum). PGPR was isolated from the soil habitat of the red chili plant in Cilegon, Indonesia. Screening was then carried out with the dual culture method on Petri dishes and tested through in vivo method on the red chili plant. The selected bacteria were characterized morphologically, biochemically, and physiologically. The results revealed that there were 14 single isolates of bacteria from the roots of the red chili plants. The five single bacterial isolates, namely Azostobacter, Azospirillum, Pseudomonas, Serratia, and Beijerinckia have good potential as PGPR based on multiple culture screening by producing clear zones and positively effect the growth of chili plants.

The bacteria that colonize plant roots and enhance plant growth by various mechanisms are known as plant growth-promoting rhizobacteria (PGPR). The functions of rhizobacteria stand substantially unexplored and detailed insights into the aerobic rice ecosystem are yet to be examined. In this study, we have isolated rhizobacteria from rice varieties grown under aerobic conditions. Seed germination test showed that strain Ekn 03 was significantly effective in stimulating germination, enhancing shoot and root length, and increasing dry matter accumulation in treated rice plants as compared to the uninoculated plants. Under greenhouse conditions, strain Ekn 03 treated rice varieties showed an overall increase in plant height by 7.63%, dry matter accumulation by 16.23%, and total chlorophyll content by 76.47%. Soil acetylene reduction assay (ARA) (4.17 nmole ethylene/g soil/h) and in-planta ARA (4.2 × 10-2 nmole ethylene/mg fresh weight of plant/h) was significantly higher in Ekn 03 treated rice variety PB 1509 under aerobic conditions. Other rice varieties showed comparable performance on inoculation with strain Ekn 03. The endophytic and rhizospheric population of antibiotic tagged Ekn 03 was higher in the roots of PB 1509 (1.02 × 104 cfu/g and 5.8 × 105 cfu/g soil, respectively) compared to other rice varieties. 16S rDNA sequence analysis revealed that strain Ekn 03 was having 100% similarity with Pseudomonas protegens. This study suggests that strain Ekn 03 can be used as a microbial inoculant in rice plants under aerobic system of cultivation. This is the first report on the application of P. protegens as PGPR in rice.

BACKGROUND Excessive nitrogen (N) fertilization in glasshouse fields greatly increases N loss and fossil-fuel energy consumption resulting in serious environmental risks. Microbial inoculants are strongly emerging as potential alternatives to agrochemicals and offer an eco-friendly fertilization strategy to reduce our dependence on synthetic chemical fertilizers. Effects of a N-fixing strain Pseudomonas protegens CHA0-ΔretS-nif on ginger plant growth, yield, and nutrient uptake, and on earthworm biomass and the microbial community were investigated in glasshouse fields in Shandong Province, northern China. RESULTS Application of CHA0-ΔretS-nif could promote ginger plant development, and significantly increased rhizome yields, by 12.93% and 7.09%, respectively, when compared to uninoculated plants and plants treated with the wild-type bacterial strain. Inoculation of CHA0-ΔretS-nif had little impact on plant phosphorus (P) acquisition, whereas it was associated with enhanced N and potassium (K) acquisition by ginger plants. Moreover, inoculation of CHA0-ΔretS-nif had positive effects on the bacteria population size and the number of earthworms in the rhizosphere. Similar enhanced performances were also found in CHA0-ΔretS-nif-inoculated ginger plants even when the N-fertilizer application rate was reduced by 15%. A chemical N input of 573.8 kg ha-1 with a ginger rhizome yield of 1.31 × 105 kg ha-1 was feasible. CONCLUSIONS The combined application of CHA0-ΔretS-nif and a reduced level of N-fertilizers can be employed in glasshouse ginger production for the purpose of achieving high yields while at the same time reducing the inorganic-N pollution from traditional farming practices. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Biocrusts provide numerous ecological functions in drylands. Recovering biocrusts via cyanobacterial inoculation recently gathered interest for ecological restoration, yet it still lacks long-term experiments to unravel biocrust community dynamics. To examine how cyanobacterial inoculants influenced local microbial community and biocrust development, we observed a 2 km2 (Qubqi Desert, China) inoculation experiment after 10 and 15 years, following biocrust formation. Our results revealed that biocrust development was in line with ecological regime shift, providing evidence for biocrust community succession, from cyanobacteria- to moss-dominated types. Associated with biocrust development, microbial communities differed significantly with less specialists compared to shifting sands. Cyanobacterial community analysis showed that Microcoleus vaginatus and Scytonema javanicum are an ideal inoculating model, as they were still dominating the community after 15 years since inoculation, while other nitrogen-fixing cyanobacteria occurred profusely with biocrust development. Biocrust community composition combined with thickness, Chl-a and exopolysaccharide measurements revealed the large variation of cyanobacterial ecological functions along biocrust development, suggesting a main function shift: from carbon fixation associated with exopolysaccharide secretion in bare sandy soils to nitrogen fixation in developed biocrusts. This large-scale field study verifies that cyanobacterial inoculation accelerates biocrust development and forwards succession, shaping the biocrust community composition over a long time.

To improve the nitrogen fixation, legume crops are often inoculated with selected effective rhizobia. However, there is large variation in how well the inoculant strains compete with the indigenous microflora in soil. To assess the success of the inoculant, it is necessary to distinguish it from other, closely related strains. Methods used until now have generally been based either on fingerprinting methods or on the use of reporter genes. Nevertheless, these methods have their shortcomings, either because they do not provide sufficiently specific information on the identity of the inoculant strain, or because they use genetically modified organisms that need prior authorization to be applied in the field or other uncontained environments. Another possibility is to target a gene that is naturally present in the bacterial genomes. Here we have developed a method that is based on amplicon sequencing of the bacterial housekeeping gene rpoB, encoding the beta-subunit of the RNA polymerase, which has been proposed as an alternative to the 16S rRNA gene to study the diversity of rhizobial populations in soils. We evaluated the method under laboratory and field conditions. Peanut seeds were inoculated with various Bradyrhizobium strains. After nodule development, DNA was extracted from selected nodules and the nodulating rhizobia were analysed by amplicon sequencing of the rpoB gene. The analyses of the sequence data showed that the method reliably identified bradyrhizobial strains in nodules, at least at the species level, and could be used to assess the competitiveness of the inoculant compared to other bradyrhizobia.

As rizobactérias promotoras do crescimento de plantas (RPCP) são capazes de proporcionar o melhor desenvolvimento vegetal por meio de diversos mecanismos. Um desses mecanismos trata da produção de reguladores de crescimento vegetal, como por exemplo, o ácido indolacético (AIA). Com isso, o objetivo do presente trabalho foi o isolamento, a caracterização fenotípica e a avaliação do potencial de produção de AIA de rizobactérias, obtidas da rizosfera de oliveiras (Olea europaea L.), visando a sua aplicação na indução do enraizamento durante a produção de mudas. Para isso, amostras de rizosfera de 17 diferentes cultivares de oliveira, do banco de germoplasma da Empresa de Pesquisa Agropecuária de Minas Gerais (EPAMIG), em Maria da Fé - MG, foram utilizadas para o isolamento de RPCP em meios de cultura JNFb, NFb e LGI, posteriormente caracterizadas fenotipicamente em meio batata-dextrose-ágar e submetidas ao teste de produção de AIA. Pôde-se observar efeito das cultivares no número de RPCP nos diferentes meios de cultura. Na caracterização fenotípica, os isolados de RPCP apresentaram alta similaridade entre si (93% a 100%). Quanto à produção de AIA, esses isolados apresentaram índices relevantes (0,16 e 29,08 μg mL-1) quando comparados a outros estudos, sendo aqueles obtidos no meio JNFb os maiores produtores. Pôde-se concluir que 11 isolados (KRJ2, GLJ2, G57J2, MFJ1, ADJ2, G57N1, AUSAL3, FTJ1, AUSAN1, AUSAJ2, KRN1), com produção acima de 20 μg mL-1 de AIA, apresentam potencial de utilização em futuros testes na indução de enraizamento de estacas de plantas de oliveira.

We aimed to develop a coating process for maize and sorghum in order to simplify the application of microbial fertilizers and increase seed resistance against insects. The coating is a thin layer of Rhizophagus fasciculatus and Rhizophagus aggregatus spores and Leifsonia sp. applied on the surface of seeds using three Arabic gum solutions as glue materials. The germinating capacities of seeds and coated inoculants were followed up to 4 months of storage between 6 °C and 25 °C conditions. The remaining seed batches were mixed with 5 days aged insects (Sitophilus zeamais and Rhyzopertha dominica). Insect emergences were daily monitored and their damages on seeds were followed. Coating with a 10% gum solution had no negative effect for maize and sorghum seed germination. Moreover, seeds can be stored for up to 4 months at 6 °C without losing their germinability. Nevertheless, coating with 15 and 20% gum decreased the germinating characteristics of sorghum small seeds. Furthermore, incorporating fungal spores through seed coating did not alter mycorrhizal spores in generating root colonization. Lastly, the coatings decreased significantly the insect emergences with less seed attacks and seed weight losses although no gum dose is able to completely stop the emergence of S. zeamais and R. dominica.

The field experiment entitled “Pre sowing seed treatment of bio inoculants and micronutrients on growth, yield and yield attributing traits of lentil (Lens culinaris L.)” var. Shekhar Masoor-2 was conducted during rabi at central reseach field of the Department of Genetics and Plant Breeding, Sam Higginbottom University of Agriculture, Technology & Sciences, Prayagraj, Uttar Pradesh, India during 2020 - 2021. The experiment consisted of 13 treatments which was laid in Randomized Block Design (RBD). Results revealed that seeds treated with T12 (Rhizobium + PSB + KMB + ZnSO4 + Ammonium molybdate) recorded maximum values in growth parameters viz., field emergence (%) 88.72%, plant height at 30, 60, 90 DAS with 6.97, 23.33, 45.2 cm Days to 50% flowering (72.67days), number of branches 5.07 branches per plant, number of pods per plant with 64.07 pods per plant, number of seeds per pod 1.85 seeds per pod. Similar results are observed in yield paramters where highest seed yield per plant was observed in T12 (Rhizobium + PSB + KMB + ZnSO4 + Ammonium molybdate) with 3.79 g and seed yield per plot 107.4 g.

Azospirillum spp. are plant-growth-promoting rhizobacteria. The surface lectins of A. brasilense strain Sp7 and A. baldaniorum strain Sp245 can attach to specific carbohydrates, and ensure the binding of the bacteria to the root surface. We investigated possible effects of A. brasilense Sp7 and A. baldaniorum Sp245 lectins on the activities of antioxidant enzymes and on the content of low-molecular-weight antioxidants in the roots of 4-day-old wheat seedlings. The roots were exposed to a number of simulated abiotic stresses: hypothermic, hyperthermic, drought, and salinity stresses. Under all stresses, both lectins increased peroxidase and superoxide dismutase activities and decreased catalase activity. The lectins differed in the intensity of induction of changes in the amounts of the low-molecular-weight antioxidants in wheat roots. They also differed in functional activity owing to their different carbohydrate specificities and structures. The data suggest broader possibilities of lectins in terms of the effect on the metabolism of host plants, and they permit adjustments to be made to the current understanding of the mechanisms that control the associative interactions between plants and bacteria.

La inoculación con rizobios y hongos micorrízicos arbusculares (HMA), de manera simple o combinada, puede contribuir con el crecimiento y establecimiento de Prosopis laevigata por una interacción positiva de los simbiontes con la planta. El objetivo fue evaluar el efecto de la inoculación simple y combinada de tres aislados locales de rizobios (R1, R2 y R3) y dos cepas de HMA (HMA1 y HMA2) en la colonización micorrízica, la nodulación, el crecimiento y producción de biomasa de P. laevigata en sustrato con pH cercano a la neutralidad. El experimento se desarrolló en invernadero, en la Facultad de Agronomía y Veterinaria de la UASLP en 2020-2021. Se evaluaron 13 tratamientos en un diseño completamente aleatorizado con cinco repeticiones. Se estudiaron las variables número de esporas g-1 de sustrato, colonización y densidad visual micorrízica, nódulos totales, nódulos efectivos, número de foliolos, altura, diámetro de tallo y rendimiento de biomasa. La inoculación promovió mayor colonización, nodulación y crecimiento vegetal con respecto al testigo sin inocular. Con HMA1, HMA2, R1, R3, R1+HMA1, R3+HMA1, R1+HMA2 y R3+HMA2, se obtuvieron resultados superiores que el resto de los tratamientos. Se concluye que la inoculación con aislados locales de rizobios y su combinación con HMA favorece el desarrollo de estructuras micorrízicas, la nodulación, el crecimiento y la producción de biomasa de P. laevigata crecido en sustrato con pH neutro. Se registró a los aislados R1, R3, las cepas HMA1, HMA2 y las combinaciones R1+HMA1, R1+HMA2, R3+HMA1 y R3+HMA2 como inoculantes efectivos para aumentar el crecimiento de P. laevigata.

Maize stover has potential as ruminant feed because it has good nutritional value and is abundant. Its perishable nature makes maize stover cannot stand for a long time. It is important to conserve maize stover especially in from of silage and utilize it during the shortage of forages period. This experiment aimed to find out the best level of Pediococcus acidilactici bacteria in the maize stover silage making. The materials used were maize stover, molasses and Pediococcus acidilactici bacteria 1x105 cfu/g and 1x106 cfu/g. The experiment used randomized block design of 3 treatments and 4 blocks. The treatments were of T1: maize stover+10% molasses; T2: maize stover+10% molasses+Pediococcus acidilactici 1x105 cfu/g; and T3: maize stover+10% molasses+Pediococcus acidilactici 1x106 cfu/g. The ensilage process was carried out for 21 days. The results showed that T3 resulted the highest quality of maize stover silage with highest DM and OM degradability (67.93% and 67.58%, respectively); 96 hours in vitro gas production (117.51 ml/500 mg DM); DM and OM digestibility (67.96% and 69.45%); NH3 concentration (19.23 mM) and microbial protein synthesis (39.56 g microbial N/kg fermented RDOM). It can be concluded that maize stover added with 10% molasses and Pediococcus acidilactici bacteria 1x106 with 21 days incubation can produce good quality of maize stover silage.

We evaluated the ability of an inoculant containing a combination of Lactobacillus hilgardii and Lactobacillus buchneri to modify the microbiome and improve the aerobic stability of whole-plant corn silage after various lengths of ensiling. Chopped whole-plant corn at about 33% dry matter (DM) was uninoculated (CTR) or inoculated with L. hilgardii CNCM I-4785 and L. buchneri NCIMB 40788 at 200,000 cfu/g of fresh forage weight each (combined application rate of 400,000 cfu of lactic acid bacteria/g of fresh forage weight; LHLB), L. buchneri NCIMB 40788 at 400,000 cfu/g of fresh forage weight and Pediococcus pentosaceus NCIMB 12455 at 100,000 cfu/g of fresh forage weight, used as a positive control (LB500), L. hilgardii CNCM I-4785 at the application rate used in the LHLB formulation of 200,000 cfu/g of fresh forage weight (LH), or L. buchneri NCIMB 40788 at the application rate used in the LHLB formulation of 200,000 cfu/g of fresh forage weight (LB). Silos were opened after 34 and 99 d of ensiling and analyzed for nutrient composition, fermentation profile, microbiome, and aerobic stability. After 34 d of ensiling, the inoculated silages had greater numbers of culturable lactic acid bacteria, a bacterial community less rich and diverse, greater relative abundance of Lactobacillus, lower relative abundance of Klebsiella, and a greater concentration of propionic acid than uninoculated silages. Inoculation decreased the ratio of lactic acid to acetic acid, except for LB alone. Treatment LHLB resulted in silage with a greater concentration of 1,2-propanediol than LB500 and was the only treatment to have a lower relative abundance of Saccharomycetes compared with uninoculated silage. Treatments LHLB and LB500 improved the aerobic stability compared with CTR, but the individual LH and LB treatments applied at a low dose did not. Whereas LB500 was stable 34 h longer than CTR, LHLB was stable 91 h longer. After 99 d of ensiling, all inoculated silages had markedly greater aerobic stability than uninoculated silage and were stable for more than 360 h. The inoculant containing a combination of L. hilgardii and L. buchneri markedly improved the aerobic stability of corn silage after a relatively short period of ensiling, and such improvements were greater than the ones obtained from inoculation with the combination of L. buchneri and P. pentosaceus. Inoculating with the combination of L. hilgardii and L. buchneri may be helpful to producers that must feed silage shortly after ensiling.

Two years field study were carried out in El-Noubaria and Sakha research station, Cotton Research Institute, Agricultural Research Center at Giza, Egypt, during 2018 and 2019 seasons. The aim of this study was to study the effects of inoculating some Egyptian cotton genotypes (Giza 97 and Giza 96) grown on clay and calcareous soils with different bio-fertilizers (Bacillus Polymxa, Bacillus megaterium, Bacillus circulans, Azotobacter and Azospirillum) on yield components and ginned cotton characteristics. Results showed that when added the bacterial strains to the soil three times at 65, 85 and 105 days after sowing through the irrigation water of cotton plants, the bio treatments improved the absorption and available of NPK leading to reproductive organ, exhibited the result higher significant values due all the treatments with using low amount of mineral fertilizers. There was a significant increase in Sakha region with clay soil for most traits compared to Noubaria region with calcareous soil, while there were no significant differences in Noubaria region for short fiber index and upper half mean. The bio treatments in most traits under study give that highly significant increased. Generally, the application of Biofertilizer improved yield and its components and ginned cotton properties of some Egyptian cotton genotypes in clay and calcareous soils.

Trophic interactions play a central role in driving microbial community assembly and function. In gut or soil ecosystems, successful inoculants are always facilitated by efficient colonization; however, the metabolite exchanges between inoculants and resident bacteria are rarely studied, particularly in the rhizosphere. Here, we used bioinformatic, genetic, transcriptomic, and metabonomic analyses to uncover syntrophic cooperation between inoculant (Bacillus velezensis SQR9) and plant-beneficial indigenous Pseudomonas stutzeri in the cucumber rhizosphere. We found that the synergistic interaction of these two species is highly environmental dependent, the emergence of syntrophic cooperation was only evident in a static nutrient-rich niche, such as pellicle biofilm in addition to the rhizosphere. Our results identified branched-chain amino acids (BCAAs) biosynthesis pathways are involved in syntrophic cooperation. Genome-scale metabolic modeling and metabolic profiling also demonstrated metabolic facilitation among the bacterial strains. In addition, biofilm matrix components from Bacillus were essential for the interaction. Importantly, the two-species consortium promoted plant growth and helped plants alleviate salt stress. In summary, we propose a mechanism in which synergic interactions between a biocontrol bacterium and a partner species promote plant health.

Plant growth promoting rhizobacteria (PGPR) are strains of naturally occurring soil bacteria that live in close vicinity to the plant’s rhizosphere region which possess the capability to augment host growth. This study was conducted to isolate and identify potential PGPR isolates indigenous to Metroxylon sagu, Rottb. rhizosphere. These potential isolates were characterised based on their beneficial plant growth promoting (PGP) properties and identified by molecular analysis via 16S rDNA sequencing. A total of 18 isolates were successfully isolated, out of which five isolates were tested, and designated as (S1A, S2B, S3A, S3C and S42). Among the five isolates, two isolates (S2B and S3C) were found to produce high levels of indole-3-acetic acid (2.96 μg/mL and 10.31 μg/mL), able to fix nitrogen and show significant activity in phosphate solubilisation. The analysis of their sequences via National Center for Biotechnology Information (NCBI) suggested their close identity towards Lysinibacillus sphaericus and Bacillus thuringiensis. It can be concluded that the isolated PGPR possesses beneficial PGP attributes. It can be implied that the isolated PGPR are potential to be used as inoculant biofertilisers, beneficial for Metroxylon sagu, Rottb. growth. Hence, further studies need to be done to evaluate the effectiveness of the beneficial microbes towards sago seedlings growth, under pot experiment.

Brazil has a long history of research with rhizobia and plant growth–promoting rhizobacteria (PGPR). Currently, the use of bio-based products in Brazil, containing microorganisms that are effective in promoting plant growth through various mechanisms, is already a consolidated reality for the cultivation of several crops of agricultural interest. This is due to the excellent results obtained over many years of research, which contributed to reinforce the use of rhizobia and PGPR by farmers. The high quality of the products offered, containing elite strains, allows the reduction and prevention in the use of mineral fertilization, contributing to low-cost and sustainable agriculture. Currently, research has turned its efforts in the search for new products that further increase the efficiency of those already available on the market and for new formulations or inoculation strategies that contribute to greater productivity and efficiency of these products. In this review, the history of biological products for main crops of agricultural interest and the new biotechnologies and research available in the agricultural market are discussed.

A study was undertaken with Troyer citrange (Citrus sinensis × Poncirus trifoliata), the rootstock of citrus, to elucidate the interaction effects of arbuscular mycorrhizal fungi and plant-growth-promoting bacteria on plant physiology under both ample watered and water stress conditions. The result exhibited significant influence of Glomus intraradices and phosphorus solubilising bacteria (PSB) (mixture of Bacillus subtilis and B. megatherium) on plant growth due to root-fungus-bacteria interaction leading to reduced accumulation of reactive oxygen species, production of antioxidant metabolites, higher anti-scavenging enzymes and higher acquisition of plant nutrients, besides enhancing rhizosphere microbial activity. Thus, Troyer citrange could be co-inoculated with G. intraradices and PSB during propagation for healthy growth of the seedlings thereby pre-ponding the budding and subsequent establishment of composite plants under field conditions. Bangladesh J. Bot. 50(3): 467-474, 2021 (September)

Nanofertilizers have gained more interest in the agricultural sector for enhancing the crop production. In addition, bionanofertilizers are eco-friendly when compared to the chemical fertilizers. Two diazotrophic Azospirillum strains were isolated and characterized from soil samples in the present study. Then, Azospirillum-capped ZnO NPs (As-ZnO NPs) was green synthesized and characterized by bio-physical techniques. UV–Vis spectrum exhibited an absorbance peak at 386 nm. The presence of diffraction peak in XRD indicates the pure crystalline form of As-ZnO NPs. The various functional molecules involved in the bioreduction of Zn+ to ZnO were noticed through FTIR spectroscopy. SEM micrograph confirmed the presence of spherical nanostructures with a mean size of 20.6 nm. A significant increase in the seed germination rate (95%) and leaf area index (LAI) (45.6%) was observed in strain 2-mediated ZnO NPs at 30 days after treatment (DAT). Similarly, following treatment with strain 2-mediated ZnO NPs (T4), the number of roots, root length, shoot length, fresh weight and dry weight were 8.4, 9.6 cm, 21.4 cm, 2.05 g, and 0.915 g, respectively. Treatment with strain 2-mediated ZnO NPs (T4), the chlorophyll A, B and AB, and carotenoid contents were 4.445, 10.36 and 10.98, and 11.08 mg g−1, respectively. The results showed that As-ZnO NPs were potential nanofertilizer and could be used in agriculture for sustainable food production. In addition, the developed nanofertilizers are eco-friendly and do not harm the environment when compared to chemical fertilizers.

Mitigation strategies based on plant–microbe interactions to increase the performance of plants under water-deficit conditions are well documented. However, little is known about a suitable consortium of bacterial inoculants and underlying physiological and enzymatic events to improve drought tolerance in maize. We performed laboratory and pot experiments to understand the synergistic interactions among plant growth-promoting bacteria to alleviate the drought-induced damages in maize. Initially, ten bacterial strains were evaluated for their osmotic stress tolerance capacity by growing them in a media containing 0, 10, 20, and 30% polyethylene glycol (PEG-6000). Also, the seeds of a drought tolerant (NK-6654) and sensitive (SD-626) maize cultivar were inoculated with these bacterial strains in the first pot experiment to determine their effects on the growth and physiological processes. Later, in the second pot experiment, the best performing inoculants were selected to study the individual and synergistic effects of bacterial inoculation to confer drought tolerance in maize. Our findings showed that the inoculation with tolerant strains resulted in higher photosynthetic activity (25–39%), maintenance of leaf water status (14–18%) and pigments (27–32%), and stimulation of antioxidant machinery (28–38%) than no inoculation in water-stressed maize seedlings. Moreover, the treatment with bacteria consortia further stimulated the drought protective mechanisms and resulted in higher efficiency of photosynthetic (47–61%) and antioxidant systems (42–62%) than the individual inoculants under water-deficit conditions. We conclude that the inoculation with microbial consortia regulates water uptake, photosynthetic performance, and stress metabolites to minimize drought-induced damages in maize.

Fe deficiency is a major challenge that limits agricultural productivity and is a serious human health concern worldwide. Under iron-limiting conditions soil microorganisms produce siderophores, that chelates Fe3+ (ferric) and make it available to the plants. Selection of efficient siderophore producing bacteria and establishing their role in enhancing iron uptake is a strategic approach for improving plant nutrition. Hence 3 efficient isolates Pantoea agglomerans, Pseudomonas plecoglossida and Lactococcus lactis, selected from a repository of 154 bacteria, producing catecholate, hydroxamate and carboxylate siderophores, respectively, were assessed for Fe chelation efficiency using 59Fe and their role in plant biometric parameters, Fe uptake and antioxidant enzymes with tomato (Strategy I) and wheat (Strategy II) test plants under hydroponic system. Cell-free siderophore preparation (Sid) improved plant parameters and iron nutrition more efficiently than bacterial inoculants. Pantoea agglomerans was proven best as its 59Fe-bound siderophore complex showed the highest uptake of 4.25 and 1.59 Bq plant−1 in wheat and tomato, respectively. Further, the Fe-starved plants (1 µm Fe-EDTA) showed around two-fold higher 59Fe uptake than those raised under Fe-sufficient condition (100 µm Fe-EDTA). Results indicated that probably the bacterial mediated iron translocation in plants is Strategy III, complementing both Strategy I and II by facilitating higher availability of chelated Fe to plant reductases directly and/or through ligand exchange with phytosiderophores, respectively. This study highlights the need for integration of siderophore based formulations in INM strategies for enhancing plant iron content to address the Fe deficiency challenge of the soil and human nutrition.

To evaluate the antimicrobial effect of high-frequency electric plasma on a cotton textile article containing planktonic cells and biofilm formation of a standard strain and a multi-resistant clinical strain of Klebsiella pneumoniae carbapenemase (KPC), and to evaluate the integrity of the post textile fiber treatment, suggesting an alternative method to control this bacterium in hospital fabrics. Based on the American Association of Textile Chemists and Colorists – 100 methodology, inoculants of the standard strain of K. pneumoniae ATCC 4352 and a clinical strain of KPC isolated from hospital infection were prepared. These were used to contaminate 100% cotton fabric samples, and the antibacterial effect of electric plasma was evaluated at 2, 3, 4, and 5 min in planktonic cells and 4, 6, 8, and 10 min in a 48-h biofilm, assessing the antimicrobial effect by colony-forming units per milliliter count and the cell viability by MTT assay, respectively. The results were statistically analyzed using the GraphPad Prism 5 program, considering P

Field experiments were conducted during the four crop seasons 2013 through 2015 on Bradyrhizobium japonicum inoculation of wheat, soybean or double inoculation of both crops under fertilization or not with NPK. Inoculation of wheat with B. japonicum gave 21 and 18% increase in grain yield and plant N uptake under fertilization regime. Pre-inoculation of wheat resulted in 23% higher nodule numbers in soybean; however, the soybean seed yield and plant N content increases were non-significant. Inoculation of only soybean increased the nodule numbers, seed yield and N content in fertilized soybean by 43, 11 and 16%, respectively; double inoculation increased it by 53, 17 and 22%. Averaged over inoculation treatments and fertilization regimes, the rhizobial numbers in soybean were 2.0× of those in wheat. The effects of chemical fertilization stimulated the rhizobial populations 2.1× over non-fertilized. Averaged over all 10-stages and both fertilization regimes, the rhizobial populations in soybean rhizosphere increased 1.8× by pre-inoculating wheat; 3.0× by inoculating only soybean and 4.3× by double inoculation over uninoculated. Overall, the symbiotic performance was: Double inoculation > Soybean inoculation > Wheat inoculation > Uninoculated. Application of Bradyhizobium inoculants to both soybean and wheat was beneficial to maximize rhizobial numbers, soybean nodulation, crop and N yield of soybean and wheat, and buildup soil organic matter and nitrogen. The additional N content in soybean and wheat by double inoculation over single soybean inoculation was ~ 40 kg N ha−1.

To investigate phylogenetic and phenotypic diversity of resident chickpea-nodulating rhizobia from Australian cropping soils. Eighty Mesorhizobium strains collected from across Australian cropping regions were analysed in a pot experiment to evaluate nodulation and symbiotic effectiveness (SE%) in chickpea plants. In vitro testing of these strains tolerant to specific stresses (pH, temperature, antibiotics, heavy metals and NaCl) was performed. In addition, phylogenetic analyses were carried out using16S-23S rRNA, atpD, recA, nodC and nifH. All strains were members of the genus Mesorhizobium based on phylogenies of 16-23S rRNA IGS and core genes. Strains with diverse 16S-23S rRNA IGS carried symbiosis genes that had high similarity to those in chickpea symbionts, suggesting the resident rhizobia in Australian soils may have acquired symbiotic traits from inoculant strains through horizontal gene transfer (HGT). Inoculation of chickpea revealed that variation in SE% among isolated strains was correlated with phylogenetic relatedness to the commercial inoculant strain Mesorhizobium ciceri CC1192. Strain A47 collected from Queensland gave the highest shoot biomass and two strains (A78 and A79) from Western Australia grew under acidic conditions (pH 4.4). In a field experiment, inoculation with four selected strains or strain CC1192 all increased shoot biomass compared with an uninoculated control; chickpea inoculated with strain A47 had the highest nodulation. Australian cropping soils contain resident chickpea rhizobial genotypes that are genetically and phenotypically diverse, with some genotypes having equal or superior SE compared with the inoculant strain CC1192. This study provides evidence to support HGT of symbiosis genes in Australian soils, and has identified strains adapted to different environmental conditions.

Products based on beneficial microorganisms, such as rhizobia, are used in agriculture to reduce or even completely replace the use of mineral fertilizers. In Brazil, rhizobia inoculants have been widely used in agriculture in the cultivation of legumes such as soybeans. Currently, the development of new formulations based on microorganisms has been made to improve the effectiveness of these products. Among these new technologies, the use of secondary bacterial metabolites has been studied to compose new formulations of inoculants. Inoculants enriched with metabolic extract from rhizobia have been showing promising results in plant growth promotion, but little is known about the isolated effects of the molecules contained in this extract, such as the lipochitoligosaccharides (LCOs), chitoligosaccharides (COs), and exopolysaccharides (EPS), when they are purified. In this study, one greenhouse and two field experiments were carried out to evaluate the effects of the addition of secondary metabolites from Rhizobium tropici CIAT 899 to the standard inoculation (SI) with Bradyrhizobium spp. on soybean nodulation, growth, and yield. Total metabolic extract containing LCOs (ME-LCO) and other secondary metabolism molecules, such as purified LCOs, COs, and EPS, were tested. In the greenhouse, it was observed that the addition of ME-LCO increased nodule number and shoot, root, and nodules dry weight in comparison to the SI. The SI + ME-LCO treatment significantly increased soybean grain yield by 7.6% compared to SI in the 2018/2019 cropping season. In 2019/2020, an increase of 3.1% was observed, but it was not statistically significant. The use of ME-LCO of R. tropici CIAT 899 in supplementation of Bradyrhizobium spp. soybean inoculants is very promising for the formulation of new generation inoculants.

Bacterial quantification by qPCR is considered the gold standard for microbial molecular diagnosis. However, a fundamental pre-requisite in this methodology is the designing of specific primers for the bacterium of interest. With the increase in bacterial genome sequencing data in the recent years, it has become possible to design specific primers that can be used to quantify different strains of the same bacterial species. To develop a real-time PCR (qPCR) protocol for the specific quantification of Azospirillum baldaniorum Sp245 strain (old Azospirillum brasilense), the Sp245 genome sequence was fragmented into small contigs with 500 base pairs each, and analyzed for similarity against the NCBI non-redundant database. A. baldaniorum-specific contigs were used to design the primers. The best pair of primers was used to quantify these bacteria after inoculation in different cultivars of Brachiaria, grown under field conditions. Our results showed that the primer pair Sp245p10 was highly specific for the Sp245 strain in the Brachiaria root and shoot field under different conditions. The qPCR assay using these primers showed differences among cultivars in the number of bacteria detected in plants after inoculation. Additionally, the number of bacteria observed in the roots was higher than that in the shoots. The qPCR methodology using a Sp245 strain-specific primer may be used to monitor A. baldaniorum inoculated into other plants and may find potential application in field experiments.

The efficacy of commercial microbial treatment on plant growth, nutrient uptake and yield is very well recognized for medicinal plants grown in field conditions. However, the use of commercial and native microbes for Cymbopogon citratus has rarely been exploited under field conditions. Therefore, in the present study we evaluated the efficacy of single and native arbuscular mycorrhizal fungal species (AMF) to mixture of mycorrhizal fungal species plus commercial plant growth promoting bacteria (PGPR) on morphological, biochemical and traits of mycorrhizal fungi associated with C. citratus. Two native AMF species, i.e. Glomus mosseae (G) and Acaulospora laevis (A), and Pseudomonas fluorescens (P) as commercial PGPR were used in this study. Three different treatments composition of selected microbes, i.e. G, G+P, and G+A+P, were utilized along control for crop production under open field conditions in a randomized complete block design. The plantlets were grown without external application of synthetic fertilizers. The results showed that the mixture of AMF and PGPR significantly increased the survival, biomass, P content of shoot as well as root, essential oil yield, and in vitro antibacterial potential of C. citratus against Escherichia coli and Staphylococcus aureus. In general, this study provides useful insight into the mixture AMF and PGPR treatment that can be applied to improve not only the biomass, phosphorus content, antibacterial potential, and yield attributes of C. citratus under open field conditions but also to improve AMF diversity in rhizosphere soil.

Drought tolerant plant growth-promoting rhizobacteria (PGPR) can confer drought tolerance in plants, when inoculated, and this effect can be more pronounced by their combined application with silicon oxide nanoparticles (SiO2 NPs). In this research, drought-tolerant and plant growth-promoting rhizobacterial strains were isolated from the rhizospheric soil of wheat plants growing in the arid region of Pakistan. Out of 30 isolated strains, three rhizobacterial strains were selected based on their drought tolerance, higher phytohormones (indole acetic acid (IAA), abscisic acid (ABA), and cytokinin (CK), and osmolyte (proline and sugar) production ability. These strains were identified as Bacillus sp. Azospirillum lipoferum and Azospirillum brasilense by 16S rRNA sequencing and accession numbers (MT482404, MT742664, and MT 742666, respectively) were obtained. Inoculation of these strains, alone and in combination, improved the germination attributes of wheat seeds under drought stress conditions. However, the combination of all three bacterial strains gave the best results. SiO2 NPs were prepared from silicon dioxide and characterized by scanning electron microscopy (SEM), Energy dispersive X-rays pattern (EDX), and UV–visible spectrum. The effect of SiO2 NPs was also tested on wheat seeds under drought stress and it was observed that SiO2 NPs (150 mg/L) create pronounced drought ameliorative potential in wheat seedlings. In the pot experiment, the combined application of SiO2 NPs and PGPR exhibited a synergistic role and improved the growth and yield of wheat. The interaction between SiO2 NPs and bacterial combination improved biomass (fresh and dry weight), and chlorophyll-a, b content by 138.78%, 65.70%, 128.57%, and 283.33% respectively as compared to untreated but drought exposed plants. They also improved relative water content (71.66%), gas exchange attributes, increased nutrients uptake, and osmolytes production of wheat. Up-regulation of antioxidant enzymes; superoxide dismutase (60.49%), peroxidase (55.99%), and catalase (81.69%) was also observed. This research work suggested that the application of SiO2 NPs and PGPR strains induced drought tolerance in wheat by modulating different physiological and metabolic processes in plants which ultimately improved the growth and yield of wheat under drought stress.

Summary The specific interaction between rhizobia and legume roots leads to the development of a highly regulated process called nodulation, by which the atmospheric nitrogen is converted into an assimilable plant nutrient. This capacity is the basis for the use of bacterial inoculants for field crop cultivation. Legume plants have acquired tools that allow the entry of compatible bacteria. Likewise, plants can impose sanctions against the maintenance of nodules occupied by rhizobia with low nitrogen‐fixing capacity. At the same time, bacteria must overcome different obstacles posed first by the environment and then by the legume. The present review describes the mechanisms involved in the regulation of the entire legume–rhizobium symbiotic process and the strategies and tools of bacteria for reaching the nitrogen‐fixing state inside the nodule. Also, we revised different approaches to improve the nodulation process for a better crop yield.

Plants interact with a great variety of microorganisms that inhabit the rhizosphere playing critical roles in several aspects of plant growth and protection against abiotic and biotic diseases. In this study, we performed a screening of bacteria associated with the rhizosphere of Prunus domestica trees to identify bacterial strains with plant growth-promoting activity. Ten strains isolated from the rhizosphere of P. domestica showed multiple in vitro plant growth promoting rhizobacteria (PGPR) activity such as the production of indole acetic acid, hydrogen cyanide, ammonia, solubilization of phosphates and antifungal activity against Verticillium dalhiae and Fusarium oxysporum f.sp. melonis. In planta, they significantly increased the growth (stem length, number of leaflets, leaf area and root weight) and biochemical (nitrate reductase activity, proline and chlorophyll content) parameters of tomato, as well as the rate of seed germination. Two selected strains (Pr7 and Pr8) with higher antagonistic activity against V. dalhiae and F. oxysporum f.sp. melonis protected tomato plants against Verticillium wilt and salt stress. In addition, they enhanced acclimatization of Vitis vinifera cv. Pinot noir and the peach root stock GF305 from in vitro to the greenhouse. 16S rRNA sequencing identified strains Pr7 and Pr8 as Pseudomonas stutzeri and Bacillus toyonensis, respectively. Since these two PGPR inoculants exhibited multiple traits beneficial to the examined host plants, they may be applied in the development of safe, and effective seed treatments as an alternative to chemical fungicides and fertilization but also for successful acclimatization of micropropagated plants., Mohamed Faize was supported by funding from the ‘Ministère de l'Enseignement Supérieur, de la Recherche Scientifique de la Formation des Cadres’ (MERSFC, Morocco) within the framework of ARIMNet2 Project

In the framework of sustainable agriculture, plant growth-promoting bacteria represent an attractive alternative. This study investigated the effect of Gluconacetobacter diazotrophicus ATCC 49037 on the growth of two commercial tomato genotypes, considering different doses, application times, and two substrate types. The application of phosphorus was also evaluated. A completely randomized five-way experimental design was applied. The results obtained on growth variables (germination percentage, cotyledon emergence time and the first, second, and third true leaf appearance times, aerial part and root dry weight) of the seedlings showed a favorable effect of the bacteria at doses of 2.5 and 5 mL of cell suspension per liter of inoculant solution, corresponding to 88 × 106 and 18 × 107 CFU mL−1, respectively. These doses had a positive interaction with the application of phosphorus in soil (0.123 g per seedling relative to the control with phosphorus of 0.065 g per seedling). The dose of 20 mL L−1 of the bacteria (70 × 107 CFU mL−1) had a negative effect on the growth variables of the seedlings (0.053 g per seedling in the presence of phosphorus and 0.023 g in its absence). The genotypes presented a differential response considering the factors assessed. The soil showed higher performance than the peat related to the variables studied. The results suggest that G. diazotrophicus at a dose of 2.5 mL L−1 with phosphorus added and its application at the time of sowing of the seeds is a promising strategy for the promotion of growth in tomato seedlings.

The present investigation on Effect of organic and inorganic sources of nutrients on flowering of hybrid gerbera (Gerbera jamesonii B.) cv. Shimmer in open field condition was conducted at Biotechnology cum Tissue Culture Centre, OUAT Bhubaneswar during 2015-16 and 2016-17. The aim of the study was to find out suitable organic and inorganic sources of nutrients for cut flower production of gerbera in open field condition. There were eight treatment combinations consisting of 100% recommended dose of fertilizer (RDF), Vermicompost, 75% RDF, PSB, Azospirillum, Azotobacter and foliar spray of macro and micro elements. Application of 75% RDF (15:10:30 g NPK/10 plants) + Vermicompost (25 g/10 plants) + Azospirillum/ Azotobacter (20 g/10 plants) + PSB (20 g/10 plants) + macro and micro element spray recorded earlier flower bud initiation and flowering. The same treatments conducted to maximum length of flower stalk, thickness of flower stalk, flower diameter, number of flowers/plant and bloom life. It can be concluded that reduced dose of chemical fertilizer (75% RDF) along with application of vermicompost and biofertiizer can improve flower yield of gerbera in open field condition.

Soybean has the potential to bring significant benefits in diversified cropping systems, which could help restructuring soil fertility and allow smallholders to increase grain yield. Rhizobium inoculation improves the biological nitrogen fixation (BNF) in legume crops and assists resource-poor farmers to increase grain yield at lower financial costs. The efficacy of symbiotic bacteria on legumes can also be improved through supplementation of phosphorus fertilizer. In this work, a meta-analysis of 29 peer-reviewed studies was performed to understand the effects of various Rhizobium strains and phosphate fertilizer application on soybean nodules. Results showed that Rhizobium inoculation was highly effective in increasing the number of soybean nodules, nodule dry weight, and shoot dry weight. Application of phosphorus fertilizer increased the overall nodule number due to improved BNF processes by Rhizobia. The main effects of both Rhizobium inoculation and phosphate fertilizer resulted in moving grain yields to 1.67 t ha-1 and 1.95 t ha-1, respectively. Furthermore, the interaction of Rhizobium inoculants and phosphorus led to relatively higher grain yield (2.51 t ha-1). Therefore, African smallholders were advised to adopt Rhizobium inoculation in soybean fields concomitantly to phosphate fertilizer application, to improve soybean productivity at lower costs. Key words: Phosphorus application, nodule number, nodule dry weight, shoots dry weight, grain yield.

The beneficial features of Bacillus thuringiensis (Bt) are not limited to its role as an insecticide; it is also able to promote plant growth interacting with plants and other plant growth-promoting rhizobacterium (PGPR). The PGPR Bt strain RZ2MS9 is a multi-trait maize growth promoter. We obtained a stable mutant of RZ2MS9 labelled with green fluorescent protein (RZ2MS9-GFP). We demonstrated that the Bt RZ2MS9-GFP successfully colonizes maize's roots and leaves endophytically. We evaluated whether RZ2MS9 has an additive effect on plant growth promotion when co-inoculated with Azospirillum brasilense Ab-V5. The two strains combined enhanced maize's roots and shoots dry weight around 50% and 80%, respectively, when compared to the non-inoculated control. However, non-differences were observed comparing RZ2MS9 alone and when co-inoculated with Ab-V5, In addition, we used co-inoculation experiments in glass chambers to analyse the plant's volatile organic compounds (VOCs) production during the maize-RZ2MS9 and maize-RZ2MS9-Ab-V5 interaction. We found that the single and co-inoculation altered maize's VOCs emission profile, with an increase in the production of indoles in the co-inoculation. Collectively, these results increase our knowledge about the interaction between the Bt and maize, and provide a new possibility of combined application with the commercial inoculant A. brasilense Ab-V5.

The goal of this study was to evaluate the efficiency of Bradyrhizobium brasilense strains native to the soil of the semiarid region in northeastern Brazil in symbiosis with soybeans in two contrasting soils in southwestern Piaui. A pot experiment was conducted using a randomized block design in a 10 × 2 factorial scheme. There were 10 nitrogen (N) sources: six native Bradyrhizobium strains [UFLA06-13, UFLA06-15, UFLA06-19, UFLA06-21, UFLA06-22 (B. brasilense), and UFLA06-24 (Bradyrhizobium sp.)], two controls with strain SEMIA 5019 (B. elkanii) and a commercial inoculant [SEMIA 5079 (B. japonicum) + SEMIA 5080 (B. diazoefficiens)] recommended for soybeans, and two controls without the application of an inoculant (one with and the other without the application of mineral N). The second experimental factor corresponded to the use of two soils (Oxisol and Quartzarenic Neosol). All strains showed increased nodulation and shoot nitrogen content in soybean plants in both soils. Most strains promoted higher nitrogen fixation when inoculated in the Oxisol. UFLA06-19, UFLA06-22, and UFLA06-24 were efficient in nitrogen accumulation in the shoots of soybeans in the Oxisol. This is the first report regarding the efficiency of B. brasilense strains in symbiosis with soybeans under different soil conditions.

Perennial legumes have potential to increase pasture productivity in the high rainfall zone (600–850 mm) of south-eastern Australia through their ability to use summer rainfall and fix nitrogen (N2). Various perennial legumes are being evaluated for this environment; however, little information exists on legume–rhizobia cross-host compatibility and its consequences for biological N2 fixation. This is especially important when legumes are sown into fields with a background of competitive rhizobia such as WSM1325 or sown as a pasture mix with different host–symbiont pairs. We studied the effectiveness and cross-host compatibility of five commercial rhizobial strains for a range of pasture legumes (nine species, 18 cultivars) under controlled environment conditions, and further evaluated nodule occupancy and competitiveness of a newly established pasture (13 species, 20 cultivars) in the field, by determining nodulation and production (biomass and N2 fixation). Three of the commercial inoculant strains formed root nodules with multiple legume species; commonly however, less N2 was fixed in cases where the inoculant was not the recommended strain for the legume species. Within a legume species, cultivars could differ in their ability to form effective root nodules with multiple rhizobial strains. White clover cvv. Trophy, Haifa and Storm, strawberry clover cv. Palestine, and Talish clover cv. Permatas formed effective nodules with both TA1 and WSM1325 rhizobial strains. White clover cultivars that could not form an effective symbiosis with the common background strain WSM1325 fixed less N2. The white clover × Caucasian clover hybrid formed effective symbiosis with strain TA1 but not with other commercial strains. Some species such as birdsfoot trefoil, Talish clover, sulfur clover and tetraploid Caucasian clover formed ineffective symbiosis in the field. Until resolved, this will likely inhibit their further development as pasture plants for similar permanent pasture environments.

Phosphate-solubilising bacteria are an important component of sustainable agriculture but their number and performance are reduced due to the presence of pesticides in soils. The potato requires a high amount of phosphorus making it a fertilizer-demanding crop. Therefore, the present study was conducted with the aim to develop pesticide-tolerant phosphate-solubilising bacterial inoculants for improving growth and phosphorus content in potato. Phosphate-solubilising bacteria were isolated from potato rhizosphere and screened for pesticide tolerance, phosphate solubilisation in the presence of pesticides and growth promotion of potato in pesticide-amended soils. Nineteen phosphate-solubilising bacteria isolated from potato rhizosphere showed phosphate solubilisation ranging from 115 to 747 µg ml−1 with significant difference among the isolates. Out of 19 isolates tested for tolerance against two commonly used pesticides in potato, two isolates showed tolerance up to 7.5 μl ml−1 (3 times the recommended dose) of chlorpyrifos and 0.75 g ml−1 (2 times the recommended dose) of carbofuran. These two pesticide-tolerant bacterial isolates also showed phosphate-solubilisation in the presence of chlorpyrifos and carbofuran, although the phosphate-solubilising ability decreased significantly with increased pesticide concentrations. The isolates were identified as Arthrobacter oxydans PR1PSB2 and Bacillus flexus PR2PSB1 based on phenotypic features, biochemical tests, and matrix-assisted laser desorption/ionisation-time of flight mass spectroscopy (MALDI-TOF–MS). The bacterial treatments Arthrobacter oxydans PR1PSB2 and Bacillus flexus PR2PSB1 alone or in combined application exhibited a significant increase in the growth parameters, phosphorus (P) content, and soil available P over the uninoculated control under greenhouse conditions in potato in the presence of pesticides. However, the plant growth promotion and P content decreased with an increase in pesticide concentrations. Pesticide-tolerant phosphate-solubilising Arthrobacter oxydans and Bacillus flexus from potato are reported for the first time.

The region around the plant root referred to as the rhizosphere, is the zone where various microbial activity occurs. It performs crucial functions such as increasing the uptake of nutrients for plant development and preventing plant against plant pathogens. Keeping in mind the beneficial role performed by rhizospheric microorganisms, rhizobacterial species were isolated from the maize and soybean plant's rhizosphere. The isolated microorganisms were evaluated for their biochemical characteristics, plant growth-promoting potentials, tolerance to different environmental conditions, and their antifungal activity against Fusarium graminearum, a fungal pathogen that infects maize. The rhizobacterial isolates with multiple plant growth-promoting potentials were identified as Bacillus spp (80.77%), Rhodocyclaceae bacterium (3.85%), Enterococcus spp (3.85%). Massilia spp (3.85%. and Pseudomonas (7.69%) species based on their 16S rRNA molecular characterization. The bacterial isolates possessed antifungal activities against Fusarium graminearum, promote maize and soybeans seed under laboratory conditions, and exhibited different levels of tolerance to pH, temperature, salt, and heavy metal. Based on this, the whole genome sequencing of Bacillus sp. OA1, Pseudomonas rhizosphaerea OA2, and Pseudomonas sp. OA3 was performed using Miseq Illumina system to determine the functional genes and secondary metabolites responsible for their plant growth-promoting potential Thus, the result of this research revealed that the selected bacterial isolates possess plant growth-promoting potentials that can make them a potential candidate to be employed as microbial inoculants for protecting plants against phytopathogens, environmental stress and increasing plant growth and productivity.

Microbial inoculants can enhance soil quality, promote plant nutrient acquisition, and alleviate problems caused by the excessive use of chemical fertilizers. However, susceptibility to harsh conditions during transport and storage, as well as the short shelf-life of plant growth-promoting rhizobacteria (PGPR), limit industrial application. Herein, a novel strategy to form nanocoating on bacterial surfaces to enhance viability was proposed. The nanocoating was composed of N-hydroxysuccinimide (NHS)-modified poly (γ-glutamic acid) (γ-PGA) and calcium ions, which could adhere to the surface of bacteria by forming covalent bonds and ionic bonds with the bacteria. The bacteria encapsulated in the coating had better resistance against harsh conditions than bare bacteria. The viability of coated bacteria was also increased by 2.38 times compared with bare bacteria after 4 weeks of storage. The pot experiment showed that coated Pseudomonas stutzeri NRCB010 had better growth-promoting properties compared with free P. stutzeri NRCB010. These results indicate that cell surface engineering is an effective method to enhance the resistance of bacteria against harsh conditions and is expected to promote the widespread use of PGPR.

Diazotrophic bacteria applied as a seed inoculant can improve the grain yield of several crops including maize. The current study aimed to test the agronomic efficiency and contribution of biological nitrogen fixation (BNF) of the endophytic diazotroph Herbaspirillum seropedicae strain ZAE94 to maize under field conditions. Eighteen field assays were conducted in four different locations during consecutive years on two hybrids and two varieties of maize in a random block design with four replicates using a peat-based inoculant. The inoculant containing the ZAE94 strain was applied without nitrogen (N) fertilization or with 40 kg N ha–1 and was compared to the application of 40 and 80 kg N ha–1 without inoculation. Crop productivity and N accumulation in the grain were evaluated in addition to 15 N natural abundance (°15 N) to evaluate BNF in the treatments without N fertilization. Fertilization at 40 kg N ha–1 plus bacterial inoculation produced crop yields similar to the treatment with 80 kg N ha–1 and increased grain N content, especially in the off-season with 40 kg N ha–1. The inoculation treatments showed lower °15N values than the non-inoculated treatments, which was most evident in the off-season. The BNF contributed about 30% of N accumulated in plants inoculated with ZAE94. On average, 64% of the N fertilized plots showed an increase of the parameters evaluated in the inoculated treatments, compared with the control. Inoculation also increased root length, root volume, and leaf area, and these parameters were positively correlated with plant weight using a hydroponic assay. This study revealed that the application of H. seropedicae inoculant increased the amount of N in plants owing to BNF, and there is a better chance of yield response to inoculation under low N fertilizer application in the off-season.

Studying the ability of potassium solubilizing bacteria (KSB) inoculants to partially replace the convential potassium mineral fertilizer (KMF) in carrot fertilizing program, in addition to, clarifying their potential cytotoxicity on mitotic chromosomes division of carrot were conducted in the present investigation. According to field and laboratory experiment results, using the potassium solubilizing bacteria (KSB) as biofertilizer positively affected yield and quality of carrot especially, KSB3 inoculate. On the same direction, KSB and KMF combinations were more efficient than those of KSB and KMF alone. Regarding to the cytotoxic studies, data reveled that carrot root tips treated with KSB and their combinations improved cell division and exhibited low cytotoxicity on mitotic division than those treated with KMF alone. So, it could be concluded that potassium solubilizing bacteria (KSB) inoculants could be used alone or mixed with low doses of KMF as alternative of potassium mineral fertilizer (KMF) in carrot fertilizing programs. In addition, it had less cytotoxicity and ecologically safer than KMF.

Trichoderma spp. are widely used as beneficial fungi for disease management, plant growth promotion, induced resistance, and abiotic stress management. Henceforth, plays a pivotal role in sustainable agriculture around the world. The study aimed to identify a promising biocontrol agent with multi-trait properties wherein isolates of Trichoderma spp. were identified on the basis of their morphological and molecular characteristics for species-level determination. Twelve Trichoderma isolates tested in-vitro against Fusarium solani and their biochemical responses concerning defense enzymes, growth enzymes, and lytic enzymes were also assessed, further validated under pot culture conditions. Under thein-vitro study, the highest percent inhibition, specific activity of defense enzymes (PO, PPO, and SOD) and lytic enzymes (cellulase, Xylanase, CMCase, and Chitinase) production were recorded with T. asperellum (TGD-I and TSH-I) and T. harzianum (MTB-I). These three isolates exhibited growth hormones ranging from 0.01 to 0.42 μl/ml (IAA) and 0.2–0.5 μl/ml (GA3) and also showed the highest root and shoot growth promotion. This study proves that T. asperellum and T. harzianum initially isolated from hot humid tropical climate may be used as bio inoculants in subtropical areas of India for biotic stress management and plant growth promotion in vegetable crops.

Slow decline disease caused by Tylenchulus semipenetrans is a major threat to global citrus production. Identification of suitable bio-agents that can be applied through a drip irrigation system by growers becomes inevitable for successful citrus production. Hence, field experiments were conducted to evaluate the effect of different liquid bio-inoculants, such as Bacillus subtilis, Purpureocillium lilacinum, and Trichoderma viride delivered through drip irrigation system on acid lime trees naturally infected with T. semipenetrans. They were applied at 4 L/ha, and their effect was compared with that of the spot application of carbofuran 3G at 100 g per tree. All tested bio-inoculants substantially suppressed the population density of T. semipenetrans in soil and acid lime roots. Among the bio-inoculants, P. lilacinum with 54.9–74.4% and 53.4–74.3% reductions in population in soil and root, respectively, performed best, followed by B. subtilis and T. viride. The effect of P. lilacinum was comparable to that of the chemical standard check carbofuran in location I, but P. lilacinum surpassed carbofuran in location II. Survival in soil and colonization on acid lime roots by P. lilacinum was higher than by B. subtilis and T. viride. The egg mass parasitization by P. lilacinum was also 7.1–7.5 times higher than by T. viride. The suppression of T. semipenetrans by P. lilacinum led to an increase in the number of fruits (19.0–23.3%), fruit weight (20.2–22.3%), and fruit yield (35.4–40.3%) in acid lime trees. The cost–benefit ratio by P. lilacinum was also higher (1: 2.6–1: 3.0), whereas it was lower in carbofuran treatment (1: 2.3—1: 2.4). It is concluded that the delivery of liquid P. lilacinum at 4 L/ha through a drip irrigation system was highly effective and economical for the management of acid lime trees infected with T. semipenetrans under field conditions.

Plant growth promoting rhizobacteria (PGPR) had the direct and indirect properties for promoting plant growth such as nitrogen fixation, phosphate and potassium solubilization. Due to the high efficiency of PGPR on enhancing plant growth, the aim of this study was to produce the new formula of biofertilizer from PGPR to promote growth of Dipterocarpus alatus. In this study, Bacillus licheniformis BDS31 and Pseudomonas azotoformans C2-114 showed the PGPR activities. Then, they were used for the production of biofertilizer in the form of granules and powder. The bacterial suspension of 1010 CFU/ml was immobilized on different substrates. The binder was polyvinylpyrolidone (PVP), starchand sodium alginate. The ratios of all components were varied and were designed into 18 formulas. The effect of physical factors on the production of both forms of biofertilizer was evaluated. The results showed that the bacteria were evenly distributed on the carriers. The granule biofertilizer with mannitol had the fastest solubility activity. Moreover, the highest number of survival bacterial cells was found in the granule biofertilizer with mannitol (Granule + M3: 59% mannitol, 10% PVP, 6% sodium alginate, 10% starch, 5% bacterial cells and10%water). The biofertilizer was applied to enhance seedling growth of Dipterocarpus alatus. The results showed that it was able to promote plant height and the number of leaves at 30 days after cultivation of plant seedlings. Such efficiency was comparable to that obtained from chemical and commercial biofertilizer. It is an effective product for use to increase crop productivity.